Apparatus for mounting components on substrate

ABSTRACT

An apparatus has a holder that receives a component from a component supply and then places the component on a substrate. In operation, it is determined whether the holder would make an interference with another component already mounted on the substrate. If this judgement is affirmative, mounting of the component held by the holder is prohibited. If, on the other hand, this judgement is negative, the component held by the holder is mounted onto the substrate.

This application is a Divisional application of Ser. No. 09/953,180,filed Sep. 17, 2001, now U.S. Pat. No. 6,718,630.

FIELD OF THE INVENTION

The present invention relates to an apparatus and method for mountingelectric components on a substrate such as a circuit board.

BACKGROUND OF THE INVENTION

Referring to FIG. 31, there is illustrated a conventional mountingsystem generally indicated by reference numeral 1. In general, thesystem 1 includes a supply section 2 for supplying electric components,a placement head 3 for receiving a component from the supply section 2and then mounting the component on a substrate such as a circuit board,a transport unit 4 for transporting the placement head 3, a recognitiondevice 5 for taking a digital image of the component held by theplacement head 3, a holding section 6 for receiving and holding thesubstrate onto which components are mounted, and a controller 7 forcontrolling an entire operation of the system 1.

In operation of the system 1, the placement head 3 moves to apredetermined position above the supply section 2 bearing a componentsupply cassette 11, for example, with a number of components 12. Avertically extending vacuum nozzle 13 in the form of a quill supportedby the placement head 3 is moved down to receive a component 12. Theplacement head 3 is then rotated about a vertical axis, i.e. Z-axis, byan angle controller 14 so that the component is oriented in apredetermined direction. The recognition device 5 takes an image of thecomponent 12, supported by the nozzle 13 of the placement head 3, movingpast a predetermined position opposing the recognition device 5. Theimage is transmitted to an image processor 20 where the image isprocessed according to a specific image processing technique todetermine a position of the component, i.e., its horizontal and/orangular displacement relative to the nozzle. Information indicating theposition of the component is transmitted to the controller 7. Based uponthe information, the controller 7 corrects the position of thecomponent. Then, the nozzle 13 is moved above a predetermined placementposition of substrate 18 and then down toward the substrate 18 so thatthe component 12 is mounted on the substrate.

FIG. 32 is a flowchart showing a conventional method for mountingcomponents. In this method, at step S1101, nozzle 13 receives component12. Then, at step S1102, recognition device 5 takes a picture of thecomponent 12 held by the nozzle 13. The picture is processed at imageprocessor 20. A position of the component 12 is determined at step S1103so as to determine whether the component 12 can be mounted on substrate18. If the component 12 is incapable of being mounted on the substrate,the nozzle 13 brings the component to a collect station (not shown) atstep S1106. Otherwise, horizontal and/or angular displacement of thenozzle 13 is determined at step S1104. Using this determineddisplacement, a horizontal position of the placement head 3 and/or anangular orientation of the nozzle 13 is adjusted. Finally, the component12 is mounted in position onto the substrate 18 at step S1105. Duringthis process, no judgement is made as to whether the nozzle 13interferes with one or more components already mounted on the substrate18.

In the meantime, electric devices are likely to be small sized andlight-weight, thereby increasing a density of components mounted onsubstrate 18 considerably. For example, a clearance between neighboringcomponents of about 1.0 mm×0.5 mm is decreased to about 0.2 mm.Notwithstanding this, each component should be mounted on the substrateso that it does not interfere with another component already mounted onthe substrate. To this end, used is a nozzle with a tip end designed tobe larger than a small component 12.

However, where clearance of components is down to about 0.1 mm, forexample, a displacement of component 12 relative to nozzle 13 may resultin an interference between the nozzle 13 and the component 12 alreadymounted on the substrate 18. This is illustrated in FIGS. 33A and 34B.In each drawing, illustrated are nozzle 13 and components (12, 12 a)both viewed from a substrate. Specifically, in FIG. 33A, the nozzle 13is shown so that it is angularly inclined relative to the component 12.In this instance, using an image of the component captured byrecognition device 5 and a result obtained by image processor 20,controller 7 corrects a horizontal and/or angular position of thecomponent 12 relative to the nozzle 13 before mounting of the component12 so that the component is placed at a predetermined, correct positionon the substrate. However, as shown by hatched lines in FIG. 33B, a partof the nozzle can result in an interference with another component 12 aalready mounted on the substrate. On the other hand, FIG. 34A shows anozzle and component retained by the nozzle in which the component ishorizontally offset from a center of the nozzle. In this instance, asshown in FIG. 34B, nozzle 13 is displaced so that the component ismounted at a correct position on the substrate, and this in turn resultsin an interference with another component 12 a already mounted on thesubstrate as shown by hatching.

Although not clearly shown in these plan views, i.e., FIGS. 33B and 34B,since the component has a certain height, interference may be moreproblematic for a case with a reduced clearance when considering adeviation of height and/or inclination of the component. That is,interference between nozzle 13 and component 12 a results in anotherdisplacement of the component 12 a. What is worse, component 12 may bedamaged, which results in a deterioration and/or malfunction of acircuit.

SUMMARY OF THE INVENTION

Therefore, a purpose of the present invention is to provide an apparatusand method for mounting a component on a substrate, which is capable ofmounting the component on the substrate without any interference betweena nozzle and a component already mounted on the substrate even when onlya small clearance is ensured between components on the substrate due toa requirement of compactness of the components.

To this end, according to the apparatus and method of the presentinvention, a holder receives a component from a component supply andthen places the component on a substrate. In operation, a judgement ismade as to whether the holder would make an interference with anothercomponent already mounted on the substrate. Then, if the judgement isaffirmative, a mounting of the component held by the holder isprohibited. If, on the other hand, the judgement is negative, thecomponent held by the holder is mounted on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart showing a method for mounting components on asubstrate according to a first embodiment of the present invention;

FIG. 2 is a flowchart showing a method for mounting components on asubstrate according to another embodiment of the present invention;

FIG. 3 is an enlarged side elevational view showing heights ofcomponents mounted on a substrate;

FIGS. 4A and 4B are diagrams for describing a determination of aninterference between a component holder and a component already mountedon a substrate;

FIG. 5 is a flowchart showing a method for mounting components on asubstrate according to another embodiment of the present invention;

FIGS. 6A and 6B are diagrams for describing a determination ofinterference according to the method of FIG. 5;

FIG. 7 is a flowchart showing a method for mounting components on asubstrate according to another embodiment of the present invention;

FIGS. 8A to 8C are diagrams for describing a determination ofinterference according to the method of FIG. 7;

FIGS. 9A to 9D are other diagrams for describing a determination ofinterference;

FIG. 10 is a schematic perspective view of a component mountingapparatus of the present invention;

FIG. 11 is a flowchart showing a method for mounting components on asubstrate according to another embodiment of the present invention;

FIGS. 12A and 12B are diagrams for describing a determination ofinterference according to the method of FIG. 11;

FIG. 13 is a flowchart showing a method for mounting components on asubstrate according to another embodiment of the present invention;

FIG. 14 is a flowchart showing a method for mounting components on asubstrate according to another embodiment of the present invention;

FIG. 15 is a schematic perspective view of another component mountingapparatus of the present invention;

FIG. 16 is a side elevational view showing a part of another componentmounting apparatus with a rotary head;

FIG. 17 is a plan view showing an arrangement of placement headssupported by the rotary head;

FIG. 18 is a block diagram showing portions of a controller of thecomponent mounting apparatus;

FIG. 19 is a table showing an example of an NC program;

FIG. 20 is a table showing an example of an arrangement program;

FIG. 21 is a table showing an example of a parts library;

FIG. 22 is a flowchart showing a process for calculating a neighboringdistance carried out by a distance calculator of FIG. 18;

FIG. 23 is a diagram showing an area occupied by a component on asubstrate;

FIG. 24 is a diagram showing a distance between neighboring areas;

FIG. 25 is a flowchart for determining interference between a holder anda component;

FIG. 26 is a flowchart showing processes carried out by a component datasection;

FIG. 27 is a perspective view of another component mounting apparatus;

FIG. 28 is a block diagram showing portions of the component mountingapparatus of FIG. 27;

FIG. 29 is an enlarged perspective view of placement heads of thecomponent mounting apparatus of FIG. 27;

FIG. 30 is a schematic plan view of the component mounting apparatus ofFIG. 27;

FIG. 31 is a schematic perspective view of a conventional componentmounting apparatus;

FIG. 32 is a flowchart showing a conventional component mountingprocess; and

FIGS. 33A-34B are schematic plan views for describing interferencebetween a holder and a component.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

With reference to the drawings, description will be made to a system andmethod for mounting a component onto a substrate or circuit boardaccording to a first embodiment of the present invention. The system ofthe present invention has an appearance that is substantially identicalto the conventional system illustrated in FIG. 31. Namely, system 1 hasa component supply 2, a placement head 3 for receiving and mounting acomponent, a robot or transport device 4 for transporting the placementhead 3, a recognition device 5 for taking a picture of a component heldby the placement head, a holder 6 for receiving and then holding asubstrate, and a controller 7 for controlling an entire operation of thesystem.

Generally, the placement head 3 causes its nozzle 13 to receivecomponent 12 from the component supply 2 and, while moving toward therecognition device 5, rotate the nozzle about its vertical axis so thatthe component orients in a predetermined mounting direction. Therecognition device 5 takes a picture of the component held by nozzle 13of the placement head 3. The picture is then processed by an imageprocessor 20 to determine a position of the component 12 on the nozzle13. The determined position is transmitted to the controller 7. Basedupon an instruction from the controller 7, the placement head 3corrects, if any, horizontal and/or angular displacement of thecomponent and then places the component in a predetermined area onsubstrate 18. Typically, the picture of the component is taken while theplacement head 3 is moving toward a placement station. However,according to the type of the recognition device 5, the placement head 3may halt while taking a picture of the component.

FIG. 1 is a flowchart showing a process for mounting a componentaccording to an embodiment of the present invention, which is carried bythe controller 7. According to this program, at step S1 component 12 isreceived by nozzle 13 of the placement head. At step S2 the recognitiondevice 5 picks up an image of the component held by the nozzle. Theimage is transmitted to and then processed by the image processor 20.Using a result obtained by the image processor 20, it is determined atstep S3 whether the component can be mounted on a substrate. If it isdetermined that the component is incapable of being mounted correctly onthe substrate, the program proceeds to step S7, causing the nozzle 13 todiscard the component at a collect station (not shown). This occurswhere the component is considerably inclined relative to a surface ofthe substrate; the nozzle bears an incorrect component; or the componentis outside a field of the recognition device so that the recognitiondevice is unable to pick up an entire image of the component.

If it is determined at step S3 that the component is in a condition suchthat it can be mounted on the substrate, the program proceeds to stepS4. At this step, another determination is made whether, during mountingof the component, the nozzle 13 would make an interference with acomponent mounted on the substrate due to horizontal and/or angularadjustment of the component held by the nozzle relative to the nozzle.This determination will be described fully together with the specificembodiments. If, on the other hand, it is determined at step S4 thatthere exists a possibility of interference between the nozzle 13 and acomponent 12 a mounted on the substrate, the program proceeds to stepS7. At this step, the component 12 held by the nozzle 13 is discarded atthe collect station (not shown). Indeed, there exists another option inwhich the nozzle 13 is moved and/or rotated to a certain extent in orderto avoid interference during mounting of the component 12, which will bedescribed in detail below. Then, the program proceeds to step S5 where ahorizontal and/or angular correction of the nozzle 13 required formounting of the component 12 is determined. Subsequently, the nozzle 13is corrected and then the component 12 is mounted on substrate 18 atstep S6. After completion of the mounting or discard of the component,the nozzle 13 moves again toward the component supply 2 for a nextpickup operation of a component. The above steps are repeated forsubsequent components to be mounted on the substrate.

Second Embodiment

Next, referring to the drawings, description will be made to a componentmounting apparatus and method according to a second embodiment of thepresent invention. Basically, structure of appearance and operation of asystem of this embodiment is similar to that of the first embodimentdescribed above, except for a process for prevention of interferencebetween a nozzle and a component.

Referring to FIG. 2, there is a process performed by controller 7. Inthis process, component 12 is supported on a nozzle at step S11. Then, aposition of the component 12 held by the nozzle is determined at stepS12, which is used at step S13 for a determination of whether thecomponent can be mounted on a substrate. If it is determined at step S13that the component is unable to be mounted on the substrate in a properway, the program proceeds to step S19 where the component is discardedat a collect station. The operations described above are the same asthose described for the first embodiment.

If, on the other hand, it is determined at step 13 that the component isheld so that it can be mounted on the substrate, another determinationis made at step S14. At this step, it is determined whether the nozzle13 makes an interference with component 12 a mounted on the substrateduring placement of the component 12 held by nozzle 13. For thispurpose, a first decision is made as to whether a height of thecomponent 12 held by the nozzle 13 is greater than that of the component12 a around which the component 12 will be mounted. FIG. 3 illustrates aspatial relationship between the component 12 held by the nozzle and thecomponent 12 a mounted on the substrate. As shown in the drawing, if theheight of the component 12 to be mounted is equal to or greater thanthat of the mounted component 12 a, no physical interference between thenozzle 13 and the mounted component 12 a will occur even when the nozzle13 overlaps the mounted component 12 a in a region indicated by α. Theheights of the components 12 and 12 a are transmitted to and then storedin controller 7 (see FIG. 31). Therefore, in this instance the programproceeds to step S17 where a horizontal and/or angular correction of thenozzle is determined in order to mount the component 12 in apredetermined position on the substrate. Based upon this determination,the component 12 is placed on substrate 18 at step S18.

If, on the other hand, the height of the component 12 is less than thatof the mounted component 12 a, a calculation is made to determine arelationship between the nozzle 13 and the mounted component 12 a, i.e.,whether the nozzle 13 would make an interference with the mountedcomponent 12 a.

FIGS. 4A and 4B schematically illustrate a spatial relationship betweenthe nozzle 13 and the component 12 held by the nozzle in which it isassumed that the component 12 is improperly inclined relative to thenozzle. In this instance, according to the conventional technique, asbest shown in FIGS. 4A and 4B, the nozzle 13 is turned around to directthe component in a proper direction, which in turn can result in aninterference between the nozzle 13 and the mounted component 12 a.

However, according to the present invention, a new concept or referencearea (safety region) 21 is used for determining whether a nozzleinterferes with a mounted component. The reference area 21 ispredetermined in light of a position of neighboring, mounted component12 a. In this embodiment, an outer periphery of the mounted component 12a defines a part of an outline of the reference area 21. Alternatively,as shown by a long and short dotted line in FIG. 4B, the reference areamay be spaced away from an outer periphery of the mounted component,leaving a certain clearance therebetween for safety.

An amount of horizontal and/or angular correction of the componentrelative to the nozzle in FIG. 4A is calculated in light of a knownconfiguration and reference position of the nozzle. Also, actualdisplacement of the component is determined by comparing an image of thecomponent taken by the recognition device with a known configuration andreference position of the nozzle. The reference position of the nozzle13, which is supposed with its center located at center 25 of the nozzle13 as shown in FIG. 4A, is stored in the controller 7 or imaging device20. Also, in order to suppose the reference area 21, also used are ashape, size and position of the component 12 a mounted on the substrate,stored in the controller 7.

Referring back to FIG. 2, using a calculation result made at step S15, adetermination is made at step S16 as to whether the nozzle 13 stayswithin the reference area 21. When even a small part of the nozzle 13 ispositioned outside the reference area, it is determined that the nozzle13 would interfer with the mounted component 12 a. Then, at step S19 thecomponent 12 is discarded from the nozzle 13 without being mounted onthe substrate. If, on the other hand, the nozzle 13 stays fully withinthe reference area 21, it is determined that no interference would occurbetween the nozzle and the mounted component 12 a. Then, the programproceeds to step S17 where horizontal and/angular displacement, or anamount of correction of the component 12, is calculated. Based upon thiscalculation, displacement of the component 12 is removed by moving thenozzle 13. Then, the component 12 is placed on the substrate at stepS18. After completion of placement or discard of the component at stepS18 or S19, the nozzle moves back to the supply section 2 for a nextpickup operation of a component. Afterwards, the program returns to stepS11 so that the above-described procedures are performed again.

A clearance between reference area 21 and an outline of a mountedcomponent may vary from one direction to another direction dependingupon features of neighboring components. Also, reference area 21 may beextended in one direction in the form of strip if no neighboringcomponent exists in that direction and, therefore, there is no necessityfor considering possible interference in that direction.

If a component held by the nozzle has a greater height than aneighboring, mounted component, it can be determined that there is nopossible interference between the nozzle and the mounted component.Therefore, in this instance, the controller performs only steps S13 toS15 for every component without making any determination at step S14.This also applies to the following embodiments.

Third Embodiment

Referring to the drawings, description will be made to another systemand method according to a third embodiment of the present invention.Basic structure of appearance and operation of the system of thisembodiment is similar to that of the first embodiment described above,except for a process for prevention of interference between a nozzle anda component.

Referring to FIG. 5, there is shown a process performed by controller 7.In this process, at step S21, component 12 is received on a nozzle.Then, a position of the component 12 held by the nozzle is recognized atstep S22, which is used at step S23 for determining whether thecomponent can be mounted on a substrate. If it is determined at step S23that the component is unable to be mounted on the substrate in a properway, the program proceeds to step S29 where the component is discardedat a collect station. The operations described above are the same asthose described for the first embodiment.

If, on the other hand, it is determined at step 23 that the component isheld so that it can be mounted on the substrate, another determinationis made at step S24. At this step, it is determined whether a height ofthe component 12 held by nozzle 13 is greater than that of component 12a around which the component 12 will be mounted. If the height of thecomponent 12 to be mounted is equal to or greater than that of themounted component 12 a, the program proceeds to step S27 where ahorizontal and/or angular correction of the nozzle is calculated. Basedupon this calculation, the component 12 is placed on substrate 18 atstep S28.

If, on the other hand, the height of the component 12 is less than thatof the mounted component 12 a, the program proceeds to step S25 where aposition of the nozzle 13 above the substrate 18 at a mounting positionof the component 12 is calculated. For example, if component 12 isinclined relative to substrate 18 as shown in FIG. 6A, calculated arepossible positions of the nozzle 13 on the substrate 18 in which thecomponent 12 is oriented in a proper direction as shown in FIG. 6B.

Based upon this calculation, another determination is made at step S26as to whether the nozzle 13 overlaps at least part of the component 12 awhich is supposed to have been mounted in a predetermined position onthe substrate 18. If an overlap is established, it is determined thatthe nozzle 13 would interfer with the mounted component 12 a. In thisinstance, the component 12 is transported to a discard station at stepS29 without being mounted on the substrate. Otherwise, the programproceeds to step S27 where an amount of horizontal and/or angularcorrection of placement head 3 is calculated. Based upon thiscalculation, a necessary horizontal and/or angular correction is made tothe placement head 3. Then, the component 12 is mounted on the substrate18. After mount or discard of the component 12, the nozzle 13 isreturned to the supply section 2 for a pickup operation of a subsequentcomponent and, then, the program proceeds again to step S21.

As described above, although in the second embodiment a reference areais considered for determination of possible interference, in thisembodiment possible interference is determined using a position in whicha neighboring component 12 a is supposed to have been mounted on thesubstrate. For this purpose, information of not only shape and size ofthe nozzle 13 but also shape and size and mounted position of component12 a are stored in the controller 7. Using this information, thecontroller 7 calculates positions occupied by the nozzle 13 and thecomponent 12 a.

Fourth Embodiment

Next, referring to the drawings, description will be made to anothercomponent mounting apparatus and method according to a fourth embodimentof the present invention. Basic structure of appearance and operation ofthe system of this embodiment is similar to that of the first embodimentdescribed above, except for a process for prevention of interferencebetween a nozzle and a component.

Referring to FIG. 7, there is shown a process performed by controller 7.In this process, at step S31, component 12 is received on a nozzle.Then, a position of the component 12 held by the nozzle is recognized atstep S32, which is used for determining at step S33 whether thecomponent can be mounted on a substrate. If it is determined at step S33that the component is unable to be mounted on the substrate in a properway, the program proceeds to step S39 where the component is discardedat a collect station. The operations described above are the same asthose described for the first embodiment.

If, on the other hand, it is determined at step 33 that the component isheld so that it can be mounted on the substrate, another determinationis made at step S34. At this step, it is determined whether a height ofthe component 12 held by the nozzle 13 is greater than that of acomponent 12 a around which the component 12 will be mounted. If theheight of the component 12 to be mounted is equal to or greater thanthat of the mounted component 12 a, the program proceeds to step S37where an amount of horizontal and/or angular correction of placementhead 3 is calculated. Based upon this calculation, the component 12 isplaced on the substrate 18 at step S38.

If, on the other hand, the height of the component 12 is less than thatof the mounted component 12 a, the program proceeds to step S35 where,as shown in FIG. 8B, irrespective of a size of the mounted component 12a, a reference area 21 a is determined from a size of component 12during image processing so that the reference area is greater than thesize of the component 12 by a certain amount. A size of an expanded areaof the reference area can be determined arbitrarily. The size of thereference area may be determined using a predetermined limit distancefrom a neighboring component, stored in the controller as shown in FIG.21.

Referring back to FIG. 7, it is determined at step 36 whether the nozzle13 stays within the reference area 21 a in light of size and shape ofthe nozzle 13, reference position of the nozzle 13 (e.g., its center25), and position of the component 12 relative to the nozzle 13determined at step S32. If not, the program proceeds to step S39 wherethe component 12 is discarded at the collect station. Otherwise, theprogram proceeds to step S37 where an amount of horizontal and/orangular correction of placement head 3 is calculated. Based upon thiscalculation, a horizontal and/or angular correction is made to theplacement head 3. Then, the component 12 is mounted on substrate 18 atstep S38. After mount or discard of the component 12, the nozzle 13 isreturned to the supply section 2 for a pickup operation of a subsequentcomponent and, then, the program proceeds again to step S31.

The size of the reference area 21 a may be varied from one direction tothe other direction according to an arrangement of components on thesubstrate, in particular, a neighboring component or components. Also,the reference area 21 a may be extended in a certain direction in theform of strip if no neighboring component exists in that direction and,therefore, there is no necessity for considering a possible interferencein that direction. Further, if there is a possible interference only inone direction, as shown in FIG. 8C the reference area may be definedonly in that direction.

In the embodiments described above, an amount of horizontal and/orangular displacement of component 12 relative to nozzle 13 is determinedby comparing a known shape and size, and a preset reference holdingposition of the nozzle 13 (e.g., a center of the nozzle 13), with animage picked up by recognition device 5. However, instead of using suchknown shape and size, and preset reference holding position of thenozzle 13, an amount of horizontal and/or angular displacement ofcomponent 12 relative to nozzle 13 may be determined from an imagepicked up by the recognition device 5 and then used for the positiondetermination. This also ensures a precise determination of whetherthere is a possible interference between the nozzle 13 and a mountedcomponent 12 a.

Also, though in the previous embodiments whether nozzle 13 interfereswith mounted component 12 a is determined by image processor 20, such adetermination may be performed by controller 7.

Further, although in the previous embodiments placement head 3 istransported in a horizontal plane by robot 4, a rotary mounting devicehaving a plurality of placement heads arranged on a circle and rotatingsuccessively for mounting, may be used instead.

Fifth Embodiment

Referring to the drawings, description will be made to a system andmethod according to a fifth embodiment of the present invention. In thisembodiment, the system has another imaging device for picking up animage of substrate 18 in order to establish a position of component 12 amounted on the substrate, and thereby to determine a possibleinterference between nozzle 13 and the mounted component 12 a. Forexample, as shown in FIG. 9A, in a previous embodiment it is determinedwhether nozzle 13, of which horizontal and/or angular position has beenadjusted, falls at least partly in reference area 22 defined by aposition of mounted component 12 a. However, a certain condition may bethought that, as shown in FIG. 9B, component 12 a is mounted on asubstrate in an inclined fashion with respect to a predetermineddirection and position. In this instance, even though nozzle 13 stayswithin reference area 22, there still exists some possibility to causeinterference between the nozzle 13 and the mounted component 12 a.However, when the component 12 a is inclined in an opposite direction asshown in FIG. 9C, no interference would occur even if a part of nozzle13 is located outside reference area 22.

Therefore, according to this embodiment, a position of mounted component12 a is obtained and then used in determination of whether nozzle 13interferes with the mounted component 12 a. For this purpose, as shownin FIG. 10, a component mounting apparatus 30 has a second imageprocessor 31 for recognition of component 12 a mounted on substrate 18.Preferably, the image processor 31 is positioned on placement head 3near nozzle 13. Other structures of the mounting apparatus 30 aresimilar to or identical to those described in the previous embodiment,so that no description is made thereto.

Referring to FIG. 11, there is shown a flowchart indicating a componentmounting process performed by controller 7. The flowchart is similar tothat described with respect to the second embodiment, except that imageprocessor 31 recognizes a position of component 12 a mounted onsubstrate 18 at step S41. This recognition is carried out afterplacement head 3 has reached a position where it places component 12 onthe substrate 18, preferably after completion of placement of component12. An image of the mounted component 12 a is transmitted to imageprocessor 20 or the controller 7 where it is used at step S47 to definea reference area.

For example, as shown in FIG. 9D, a deformed reference area 22 a may bedefined for inclined component 12 a. The deformed reference area 22 aensures to prevent interference between nozzle 13 and component 12 aplaced improperly. Also ensured is a proper mounting of component 12,which would be prohibited from being mounted when supposing anon-deformed reference area as shown in FIGS. 9A to 9C. The imageprocessor 31 may be provided on another moving member rather than theplacement head 3. In this instance, the image processor 31 with themoving member may oppose the substrate 18 for recognition of thesubstrate while the placement head 3 is away from the substrate 1.

Sixth Embodiment

Referring to the drawings, description will be made to another systemand method according to a sixth embodiment of the present invention. Inthis embodiment, component 12 which is discarded due to possibleinterference between a nozzle and a mounted component is allowed to bemounted on substrate 18 by adjusting a horizontal and/or angularposition of the nozzle while preventing interference of the nozzle andthe mounted component. That is, in the second embodiment, as shown inFIG. 4B if the nozzle 13 protrudes beyond reference area 21, component12 is discarded without being mounted on substrate 18. However, as shownin FIGS. 12A and 12B, even in the same condition nozzle 13 rotates in adirection indicated by arrow 27 so that it stays wholly within referencearea 21, allowing component 12 to be mounted on substrate 18. This notonly prevents interference between the nozzle and a component on thesubstrate, but also increases an efficiency of mounting.

Although in this embodiment the nozzle 13 is rotated into the referencearea, the nozzle may be transported linearly in a direction away fromcomponent 12 a on substrate 18. Also, the rotational movement may becombined with linear movement.

The above adjustment of the nozzle 13 can cause component 12 to inclineas indicated by a solid line, relative to a proper position on thesubstrate indicated by a long and short dotted line 12 b. This mayincrease a likelihood of interference between component 12 a mounted onthe substrate and the nozzle 13 during placement movement for asubsequent component. However, interference is prevented by reducing asize of reference area 21 according to inclination in formation of aregion for the subsequent component. The nozzle 13 is discarded unlessthe nozzle 13 enters entirely within the reference area.

FIG. 13 is a flowchart showing a component mounting method of thisembodiment. In this flowchart, processes performed at steps S11 to S19are the same as those described with regard to the second embodiment ofthe present invention. If it is determined at step S16 that nozzle 13 isoutside a reference area, another determination is made at step S61 asto whether the nozzle would be entirely within the reference area bylinear and/or rotational movement of the nozzle. If the result isaffirmative, a position of the nozzle is adjusted at step S17 so thatthe nozzle stays entirely within this region. Then, a component held bythe nozzle is mounted on the substrate at step S18. Otherwise, thecomponent 12 is discarded at a collect station.

Although this embodiment has been described in combination with thesecond embodiment, it can equally be combined with other embodimentsdescribed above using a reference area. In particular, in combination ofthis embodiment with the fifth embodiment, since possible interferenceis determined after recognition of position of component 12 a on asubstrate, inclination of component 12 provides no adverse affect withrespect to mounting of a subsequent component.

Seventh Embodiment

Referring to a flowchart in FIG. 14, description will be made to anothersystem and method according to a seventh embodiment of the presentinvention. In this embodiment, data of interference between nozzle 13and component 12 a on substrate 18 is collected during a process ofmountings for one or more than a certain number of substrates. Then, thecollected data is used for protection against interference duringsubsequent mountings. For example, in mountings for a predeterminednumber of substrates, interference data including the number, degree,and position of possible interference caused between a nozzle and acomponent is memorized. This data is processed statistically, forexample, to obtain a tendency of interference or inclination. Thistendency shows, for example, when and/or where interference is likely tooccur. Therefore, if that tendency is confirmed at step S72, anadjustment is made to cancel or reduce the tendency, thereby preventinginterference between nozzle 13 and component 12 a on substrate 18.

The adjustment may be made by rotation and/or horizontal movement ofcomponent 12 to be mounted and/or component 12 a mounted on thesubstrate. If, by this adjustment, a former tendency is eliminated butanother tendency is presented in a predetermined number of subsequentmountings, a further adjustment is made to cancel or reduce the lattertendency. In this instance, adjustment may be made to either or both ofcomponents 12 and 12 a. When adjusting both components, an amount ofadjustment may be divided substantially equally for two components.

Eighth Embodiment

Referring to the drawings, description will be made to another systemand method according to an eighth embodiment of the present invention.As described with reference to FIG. 3, when the height of a mountingcomponent 12 is greater than that of a mounted component 12 a, nointerference will occur between nozzle 13 and the mounted component 12a. This in turn means that no interference would be made by mountingcomponents in an order in which a shorter component is mounted earlierthan a taller component. Therefore, according to this embodiment,components are mounted in a reverse order of their height, therebypreventing interference of a nozzle and a mounted component orcomponents without any necessity of defining a reference area, or ofrecognizing a size of the mounted component or components.

In this case, it is not necessary to determine a mounting order for allcomponents to be mounted on the same substrate. This is because nozzle13 may interfere only with a component 12 a positioned in an area inwhich component 12 will be mounted, and may not interfere with acomponent 12 a positioned away from the area. Then, it is advantageousto define several blocks on the substrate, each of which includes onlycomponents that would cause interference between the nozzle and amounted component. In this instance, an order of mounting of componentsis determined for each block. Also, it is unnecessary to determinepossible interference between the nozzle holding a component to bemounted in one block and a mounted component or components in anotherblock away from the one block. Each height of the components to bemounted on one substrate is available from component data pre-stored incontroller 7.

Ninth Embodiment

Referring to the drawings, description will be made to another systemand method according to a ninth embodiment of the present invention. Inthis embodiment, interference determination using reference area 21 isperformed for a rotary type component mounting apparatus.

As shown in FIGS. 15 and 16, a component mounting system 100 generallyincludes a component supply section 110 for supplying electroniccomponents successively, a rotary head 112 for receiving and thenmounting the components on a substrate 18, and an X-Y table 114 forpositioning the substrate. With this arrangement, the substrate 18 issupplied from a substrate supply section 116 and then positioned on theX-Y table 114. The rotary head 112, on the other hand, receivescomponents 12 from the component supply section 110. A position of eachcomponent on the rotary head 112 is corrected, if necessary. A correctedcomponent is then mounted on the substrate 18. After completion ofmountings of the components, the substrate is transported from the X-Ytable to a substrate discharge station 118.

In addition, the mounting system 100 has an input section 120 for datainput, a display station 122 for data display, and a controller 107 forcontrolling operations of devices in the system. Input data includessizes of components and control data, and display data includes datashowing a condition of the devices in the system.

Referring to FIG. 16, the component supply section 110 has a set ofparallel parts cassettes 11 each holding a number of electroniccomponents 12. The set of parts cassettes is supported so that it canmove back and forth in a direction perpendicular to the drawing, whichensures that each of the parts cassettes is to provide a component for acomponent supply region 110 a. The X-Y table 114 is supported so that itmoves between the substrate supply section 116 and the substratedischarge section 118. At the substrate supply section 116, the table114 reaches a position communicated with a substrate inlet where itreceives a substrate 18 on which components will be mounted. Then, thetable 114 holds and then transports the substrate 18 into a placementposition where components are mounted thereon by the rotary head 112. Atthe placement position, the table 114 moves left to right and back andforth so that each component is mounted at a predetermined,corresponding position on the substrate. After completion of mountingsof the components, the table 114 moves to a position adjacent to thesubstrate discharge section 118 for discharge of the substrate to thesubstrate discharge station 118.

For example, as shown in FIG. 17, the rotary head 112 has 12 placementheads at regular intervals on its periphery. Each of the placement heads126 has five nozzles 132 for holding components of different sizes, andis supported so that it moves up and down and rotates about a central,vertical axis thereof. This allows that, when receiving and mounting acomponent, each nozzle 132 takes an outermost position on a circleindicated by a long and short dotted line in FIG. 17.

In operation, each placement head 126 is transported by index rotationof rotary frame 128 from component supply position 110 a of thecomponent supply section 110 to an opposite, component placementposition, and then back again to the component supply position 110 athrough various stations.

Discussion will be made to operations carried out at each station. Atstation 1 (ST1), i.e., drawing station, nozzle 132 faces a componentsupply position and receives component 12 from component supply section110. Then, a thickness of the component held by nozzle 132 is measuredat ST3 by a two-dimensional line sensor (not shown), which thickness isthen transmitted to the system 100. The system 100 determines whetherthe thickness measured is less than a predetermined value. If thisdetermination is affirmative, the system recognizes that no component issupported by the nozzle, or the component is incorrectly supported bythe nozzle. Otherwise, at ST4 (i.e., pickup station), a two-dimensionalCCD camera (i.e., displacement detector) picks up a plan image of thecomponent held by nozzle 132 from below. Using this image, a horizontaland/or angular displacement of the component is determined, which isthen transmitted to the system 100. At ST6, the nozzle rotates about itsvertical axis according to determined, horizontal and/or angulardisplacement to orient the component in a proper direction.

At ST7 (i.e., mount station), by use of a result obtained from the imageprocessor, the X-Y table is positioned. Then, placement head 126 movesdown to place the component onto substrate 18 in position. If it hasbeen determined at ST3 or ST4 that the component is incorrectlysupported on the nozzle, or a wrong component is supported on thenozzle, the component is discarded from the nozzle at respectivestations. At ST11 (i.e., nozzle select station), placement head 126 isrotated about its vertical axis, depending upon a component to bemounted, to place a corresponding nozzle 132 into an outermost positionon circle 134.

Angular displacement may be corrected by rotation of the placement head.This results in a further horizontal displacement of a component, whichis eliminated by movement of the X-Y table.

Next, discussion will be made to an embodiment for mounting a componentby the system 100. This method is featured in that a determination ismade as to whether a nozzle or a component supported on the nozzle wouldmake an interference with a component mounted on a substrate, by use ofvarious criteria.

For this purpose, as shown in block diagram of FIG. 18, system 100includes various portions for its controlling. Controller 107 has an NCdata store section 141 for storing data defining a mounting position ofeach component on a substrate; an arrangement data store section 142 forstoring data of a supply position of each component defined in the NCdata, and types of components; a component data store section 143 forstoring data defining features such as a shape of each component and atype of each nozzle; a nozzle size data store section 144 for storingdata defining a size of each nozzle; a calculator 145 for calculating adistance between every two neighboring components on the substrate inboth, X and Y directions using data provided from the stores 141, 142,and 143; a distance data store section 146 for storing distancescalculated by the calculator 145; and an interference judge 148 forjudging existence of a possible interference using data from the datastore section 146, and also determining a suitable clearance for eachcomponent and a mounting position.

In order to mount components onto a substrate, the system 100 includesan NC program, arrangement program, and component library, for example,stored therein. As shown in FIG. 19, the NC program 151 defines an orderof components to be mounted and has supply positions (Z-number) andplacement positions (X- and Y-coordinates) of the components. As can beseen from the drawing, one line of such data is prepared for eachcomponent.

As shown in FIG. 20, the arrangement program 152 defines data thatincludes a shape of a component for each Z-number by use of anassociated code in order to distinguish a type of component to besupplied.

As shown in FIG. 21, the component library 153 defines data of componentshape code, component feature code, operational condition, supplycondition, and neighboring condition. For example, the component shapecode defines a type of a component. The component feature code defines asize of the component. The supply condition defines how and by what thecomponent is to be supplied. The neighboring condition defines a size ofa nozzle and a clearance between neighboring components on a substratein order to determine a possible interference between the nozzle, or acomponent to be mounted, and a mounted component.

Possible interference can be determined using a constant, limit distancedefined for prevention of the interference. However, in this procedurenothing is considered about the neighboring condition of components.Therefore, according to the present invention, the limit distance isautomatically determined by taking into account the neighboringcondition for mounting of each component, rather than using a constantlimit distance.

The NC program 151, arrangement program 152, and component library 153are established and stored prior to actual mounting of components. Then,a program for mounting is generated by a combination of the NC program151, corresponding to a substrate on which components are mounted, andthe arrangement program 152 defining component supply positions andshapes of components designated in the NC library 153 with componentshape codes.

FIG. 22 shows a flowchart for using distance calculator 145 to calculatea distance between two neighboring components mounted on a substrate. Inthis flowchart, at step S111 NC data store section 141 provides amounting, horizontal and angular position (x and y coordinates and θ) ofa component on the substrate. At step S112, the arrangement data storesection 143 provides a shape code of the component. Then, at step S113the component data store section 143 provides dimensions in the x and ydirections of a component corresponding to the shape code. The distancecalculator 145 calculates an area (x_(S), y_(S)) on the substrate to beoccupied by the component at step S114. The area (x_(S), y_(S)) isstored in distance data store section 146.

For example, the area (x_(S), y_(S)) is defined by the followingequations:

$\begin{matrix}{{x_{p} - \frac{\left( {{L\;\cos\; R} + {W\;\sin\; R}} \right)}{2}} \leq x_{s} \leq {x_{p} + \left( \frac{{L\;\cos\; R} + {W\;\sin\; R}}{2} \right)}} & (1) \\{{y_{p} - \frac{\left( {{L\;\sin\; R} + {W\;\cos\; R}} \right)}{2}} \leq y_{s} \leq {y_{p} + \left( \frac{{L\;\sin\; R} + {W\;\cos\; R}}{2} \right)}} & (2)\end{matrix}$wherein, as shown in FIG. 23,

-   x_(p), y_(p): coordinates of a center of the component,-   R: angle of the component, and-   L, W: dimensions of the component.

This calculation is performed for every component to be mounted on thesubstrate at step S115. Then, an area of one component P is providedfrom the distance data store section 146. Next, another componentproviding a minimum distance from the component P in either direction isdetermined. This process is illustrated in FIG. 24 in which, for onecomponent P, selected in x-direction is component Pl that provides aminimum distance Δx from the component P, and selected in y-direction isanother component Pu that provides a minimum distance Δy from thecomponent P. For example, as shown in FIG. 24, the x-coordinate (x_(l))of the center of the selected component Pl and the y-coordinate (y_(u))of the center of the selected component Pu are defined as follows:χ_(l min)≦χ_(ls)≦χ_(l max)  (3)Y_(u min)≦Y_(us)≦Y_(u max)  (4)Then, a minimum distance in the x- and y-directions from the componentsPl and Pu, respectively, are determined as follows:ΔΔχ=χ_(p min)−χ_(l max)  (5)Δy=y_(u min)−Y_(p max)  (6)wherein x_(lmin) and x_(lmax) are minimum and maximum x-coordinates ofthe component Pl, respectively, Y_(umin) and Y_(umax) are minimum andmaximum y-coordinates of the component Pu, respectively, and x_(pmin)and Y_(pmax) are minimum x-coordinate and maximum y-coordinate of thecomponent P, respectively. The calculated distance Δx and Δy are storedin the distance data store section 46 at S117.

Referring to FIG. 25, there is shown a flowchart of a procedure fordetermination of possible interference of a component, performed beforemounting of components 12. In this program, according to a preset mountprogram, among a number of parts cassettes prepared at the componentsupply 110, one parts cassette 11 bearing a desired component 3designated by the mount program is moved to the component supplyposition 110 a. Component 12 is received by nozzle 132 of placement head126 positioned at the component supply section ST1 of the rotary head110 a at step S121.

Then, the rotary head 112 is subject to index rotation to transport theplacement head 126 with the component into the recognition station ST4where the component is recognized by a two-dimensional CCD camera atstep S122. The image recognized by the recognition device is used todetermine a relative relationship between nozzle 132 and component 12 inthe x and y directions at step S123. That is, at this step, offsets ofthe nozzle 132 from the component 12 in the x- and y-directions aredetermined. Each offset bears a plus or minus sign. Then, neighboringdistance information for the component supported by the nozzle isretrieved from the distance data store section 146 at step S124. Then,another determination is made at step S125 as to whether offset of thenozzle 132 from the component, calculated at step S123, is less than theneighboring distance retrieved in either direction. If the offset isgreater than the neighboring distance, there exists a possibleinterference between the nozzle, or the component supported on thenozzle, and another component mounted on the substrate. Therefore, atstep S126 the placement head 126 is moved to discard station ST6 wherethe component is released from the nozzle into a collect container (notshown). The same component is then picked up again by the nozzle and, ifthere is no possible interference, mounted at a position of thesubstrate where the discarded component was intended to be mounted. If,on the other hand, the offset is less than the neighboring distance, thecomponent is mounted at step S127 at a predetermined position of thesubstrate. If it is determined that the above steps have been performedfor every component, the program is completed at step S128.

According to the mounting method of this embodiment, data isautomatically generated for determining interference between a nozzle,or component supported on the nozzle, and another component mounted on asubstrate for the nozzle and each component. This eliminates acomplicated input process of respective neighboring distances atgeneration of a mounting program. Also, conventional data can be used inthis method without any necessity of modification. This means that nocomplicated operation is needed for input of new data for a mounting.Also, possible interference is checked for each component independently,which prevents unwanted discard of a component capable of being mounted.This ensures an effective mounting of components. Further, immediatelyafter discard of one component, the same component is mounted on thesubstrate without moving the rotary head, which ensures a reduction oftotal time for this mounting.

Tenth Embodiment

Discussion will be made to another system and process for mounting of acomponent according to a tenth embodiment of the present invention.Generally, in this embodiment, data of components mounted on a substrateare used for determination of possible interference.

This method is preferably used in the system 100 shown in FIGS. 15 to17. In particular, in addition to structures shown in FIG. 18, thesystem 100 further includes a memory section 147 for holding a list ofpositions of components mounted on a substrate, which list isdynamically updated after mounting of each component. A nozzleinterference check section 148 determines, for each component supportedon a nozzle, whether it will make an interference with any componentmounted on a substrate using data from the memory sections 144, 146 and147. For each determination, a suitable neighboring limit distance iscalculated for each component and its position.

Referring to FIG. 26, there is shown a flowchart indicating procedurescarried out at the memory section 147 in FIG. 18 during mounting of acomponent. For example, when a new substrate is introduced into thesystem 100, the memory section 147 clears a list of positions ofcomponents mounted for a previous substrate at step S131. After a newcomponent is supported on a nozzle at step S132, it is determined atstep S133 whether other components neighboring the new component on thesubstrate has been mounted on the substrate. If a neighboring componenthas already been mounted on the substrate, an interference check is madeonly for that neighboring direction according to procedures described inthe ninth embodiment at steps that follow step S134. Otherwise, nointerference check is made and the component supported by the nozzle ismounted on the substrate at step S139.

According to the mounting method of this embodiment, if data shows apossibility of interference between neighboring components but nointerference would occur when considering actual mounting, aninterference check is eliminated. This means that minimum checks arecarried out, thereby shortening a time for mounting of each component.

In this embodiment, when it is determined that the nozzle or a componentsupported on the nozzle would interfer with a mounted component, thesupported component is discarded without being mounted on a substrateand then another component is held by the nozzle for its mounting. Inthis instance, however, the system may simply be de-energized and thenprovide a warning to an operator of this system. This allows theoperator to determine whether the component supported on the nozzleshould be discarded.

Although the ninth and tenth embodiments have been described incombination with the system 100 having rotary head 12, they are equallyapplied to system 1 in which a placement head moves back and forth on asubstrate fixed in the system shown in FIG. 31, and another system shownin FIGS. 27 and 30 in which a placement head has a plurality of nozzlesfor supporting plural components simultaneously (see FIG. 29). Devicesequipped in the system in FIG. 27 are operationally connected to eachother as shown in FIG. 28.

System 200 has a guide portion including a pair of guide rails 252 eachextending from a substrate supply section 216 through a substratesupport section 217 to a substrate discharge section 218, and eachlocated at a center of a base frame 250. This allows for substrate 18introduced at the supply section 216 to be transported to the supportsection 217, where components are mounted thereon, and then dischargedfrom the discharge section 218. The base frame 250 arranged above thesubstrate 18 is provided on its opposite sides with y-axis robots 260and 262, which in turn support an X-axis robot 264 so that by driving ofthe y-axis robots 260 and 262 the x-axis robot moves back and forth inthe x-direction. This allows a placement head 266 to be movedhorizontally in the x- and y-directions. Each robot has a transportmechanism. For example, the transport mechanism has a nut secured to amovable member, and a threaded shaft secured to a fixed member anddrivingly connected to a motor so that, by driving of the motor, theshaft rotates to transport the movable member back and forthalternately.

The placement head 266 supported by X-Y transport mechanism, with thex-axis robot 264 and y-axis robots 260 and 262, supports a component byits nozzle 232 for placement onto a substrate at a predeterminedposition of the substrate. The component may be a circuit chip such as aresistor or condenser supplied from a parts cassette, for example, andanother large electronic device such as an IC connector (e.g., SOP orQFP) supplied from a parts tray, for example. Mounting procedures arecontrolled by controller 207 in FIG. 28 according to a program memorizedand preset in memory 1001. The program may be inputted by manually usingkeys prepared at an operation panel, for example.

The parts cassettes 11 are arranged on opposite sides of the pairedguide rails 252, e.g., on the right upper and left lower sides. Eachparts cassette 11 has a strip-like component holder wound about a reeland holding a number of components or circuit chips such as resistorsand condensers. The parts tray 268, on the other hand, can support apair of two trays 268 a extending perpendicularly to the guide rails,respectively. Each tray 268 a slides toward the guide rails 252according to the number of components to be supplied so that a componentsupply portion stays at a predetermined pickup position with respect tothe y-direction. Typically, each tray 268 a supports a number ofelectronic components such as QFPs.

An image processor 220 is provided near a substrate positioned by thepair of guide rails 252 in order to detect a two dimensionaldisplacement or a position of a component supported by nozzle 232, andalso to cancel displacement by movement of the placement head 266. Theimage processor has a recognition device at its bottom and a housingsurrounding the recognition device. A number of light emitters such aslight emitting diodes are provided stepwise inside the housing forillumination of a component supported on the nozzle. This allows forlight to be emitted from various directions toward a mounting surface ofthe component, which ensures picking up a clear image of the componentwith a suitable angle irrespective of the type of the component. Anangle is predetermined for each component according to preset componentrecognition data. An image picked up by the image processor 220 isprocessed by the controller to determine a center of the component andpositions of electrodes to be used for correction of placement positionand/or angle.

As shown in FIG. 29, transport head 266 has a component holder or amultiple head with a plurality of placement heads (e.g., first to fourthplacement heads 226 a to 226 d of the same structure). Each placementhead has a nozzle 232, an actuator 278 for moving the nozzle 232 up anddown, and a pulley 284. Pulleys 284 of first and third placement heads226 a and 226 c are drivingly connected through a timing belt 282 to aθ-rotation motor 280 a so that the nozzles 232 of these heads can rotateabout respective vertical axes thereof simultaneously. Pulleys 284 ofsecond and fourth placement heads 226 b and 226 d are connected throughanother timing belt 282 to another θ-rotation motor 280 b so that thenozzles 232 of these heads can rotate about respective axes thereofsimultaneously. Each actuator 278 is made of an air-cylinder, forexample, so that by turning on and off the air-cylinder the nozzle 232moves up and down for receiving and holding a component. Although asshown in FIG. 29 rotation of the motor 280 a is transmitted through onetiming belt to rotate the nozzles 232 of the placement heads 226 a and226 c, and rotation of the motor 280 b is transmitted through anothertiming belt to rotate the nozzles 232 of the placement heads 226 b and226 d, each of the placement heads 226 a-226 d can be connected to anindividual motor for its θ-rotation. However, in order to reduce weightof a unit of the placement heads, the number of motors is minimized.

Each nozzle 232 of the placement heads is replaceable, and spare nozzlesare accommodated in a nozzle stacker 286 mounted on the base frame 250of system 200. Generally, various nozzles are used such as small sizednozzles for the chips of about 1.0 mm×0.5 mm, and medium sized nozzlesfor QFPs of about 18 mm×18 mm.

In operation, substrate 18 is introduced at the supply section 216 ofthe paired guide rails 252 and then transported into the holding section217. Then, placement head 266 is moved by the X-Y robot transversely orhorizontally in an X-Y plane to receive a predetermined component fromthe parts cassette 11 or parts tray 268. This component is then passedby a recognition device of the image processor 220 to recognize aposition of the component supported by a nozzle. Using the position ofthe component, a motor rotates the nozzle 232 for correction of positionof the component, if necessary. Then, the component is placed at apredetermined component mounting position on the substrate 18.

Each of the placement heads 226 a-226 d moves down the nozzle 232vertically, i.e., in the z-direction, by driving of actuator 278 whenreceiving a component from parts cassette 11 or parts tray 268, and alsowhen placing a component onto substrate 18. Also, a nozzle is replaceddepending upon the type of the component.

By repetition of receiving and mounting, all components are mounted on asubstrate. A substrate onto which every component has been mounted istransported from the holding section 217 to the discharge section 218.Then, a new substrate is introduced from the supply section 216 into theholding section 217 where components are mounted on this substrate.

An inertial force generated by acceleration and deceleration of acomponent, and an adhering force between the component and a substrate,should be considered when deciding a vacuum force applied from a nozzleto the component. Therefore, components are divided into several groups,i.e., high speed, medium speed, and low speed mounting componentsdepending upon weight and size thereof.

Also, a plurality of placement heads may be used for simultaneousreceiving and/or mounting of components.

In operation of the system 200, distance between all neighboringcomponents is calculated according to the program shown in FIG. 22, andthen stored in the memory unit 146. As shown in FIG. 30, substrate 18 istransported from the supply section 216 into the holding section 217. Onthe other hand, a component is picked up from parts cassette 211 or patstray 268 by placement head 216 driven according to a mounting program.Next, similar to the ninth and tenth embodiments, possible interferenceis checked for a component supported on a nozzle according to theflowchart shown in FIG. 25. For this purpose, while the placement headmoves above the image processor 220, the recognition device takes apicture of the component supported on the nozzle. Using the image pickedup by the recognition device, position or displacement of the componentrelative to the nozzle is determined. Then, it is determined whetherdisplacement of the component relative to the nozzle is less than aneighboring distance derived from the data unit 146. If the displacementis greater than the neighboring distance, the component is discarded.Otherwise, the component is mounted on the substrate. An interferencecheck between the nozzle, or component supported on the nozzle, and acomponent mounted on the substrate is performed as described in thesecond embodiment.

Eleventh Embodiment

Discussion will be made to the eleventh embodiment of the presentinvention. This embodiment is directed to a computer readable recordingmedium. In this medium, a program having procedures for judging possibleinterference between nozzle 13, 132, and 232 and a mounted component 12a is recorded therein. For example, the program has several steps of

-   receiving a component from the component supply by the component    holder;-   recognizing a component supported by the component holder;-   using a result of the component recognition and determining whether    the component is supported properly by the component holder;-   when it is determined that a component is supported by the component    holder so that this component will not be mounted properly,    discarding the component to a collect station;-   when, on the other hand, it is determined that a component is    supported by the component holder so that this component will be    mounted properly, determining whether a height of the component is    greater than that of a component mounted on a substrate;-   when it is determined that the height of the component is less than    that of a mounted component, determining whether the component    holder would make an interference with the mounted component during    mounting of the component supported on the component holder;-   when it is determined that the component holder would make    interference with the component mounted on the substrate, discarding    the component supported by the component holder into a collect    section without mounting the component supported by the component    holder;-   when it is determined that the component holder would not make an    interference with the component mounted on the substrate,    determining whether a height of the component supported by the    component holder is greater than that of a neighboring component    mounted on the substrate; and-   when it is determined that the height of the component supported by    the component holder is greater than that of the neighboring    component mounted on the substrate, calculating an adjustment for    correcting horizontal and/or angular displacement of the component    supported by the component holder relative to the component holder.

The process has been described in detail in connection with anotherembodiment and, therefore, no further discussion will be made thereto.

The recording medium is preferably used for a system described inconnection with the second embodiment, for example. Also, a programrecorded in the recording medium is installed and then carried out incontroller 7, 107, or 207.

Although in the process recorded in the medium a component supported bythe component holder is discarded if it is determined that thiscomponent would make interference with another component mounted on asubstrate, a horizontal and/or angular position of the nozzle and/or thecomponent supported by the component holder may be adjusted so as not tointerfere with the component mounted on the substrate during mounting ofthe component supported by the component holder, rather than discardingthe component as described in connection with the sixth embodiment.Likewise, processes described in connection with other embodiments canalso be memorized in respective recording mediums. In this case, each ofthe recording mediums is used for installation of a program intocontroller 7, 107, or 207.

In conclusion, the present invention prevents interference between acomponent holder, or a component supported by the component holder, andanother component already mounted on a substrate even though thereremains a slight clearance between the components, thereby producing ahigh quality substrate on which components have been mounted.

1. An apparatus for mounting a component onto a substrate, comprising: acomponent supply device for supplying a component to be mounted onto asubstrate; a holder for receiving the component from said componentsupply device and holding the component; and a controller for (i)prohibiting said holder from mounting the component, when held by saidholder, onto the substrate when said controller makes a judgement thatsaid holder would make an interference with another component mounted onthe substrate were the component held by said holder attempted to bemounted onto the substrate, and (ii) causing said holder to mount thecomponent, when held by said holder, onto the substrate when saidcontroller makes a judgement that said holder would not make aninterference with another component mounted on the substrate were thecomponent held by said holder attempted to be mounted onto the substratewherein said controller is also for correcting a position of said holderrelative to the substrate, when the component is held by said holder andsaid controller makes the judgement that said holder would make aninterference with the another component mounted on the substrate werethe component held by said holder attempted to be mounted onto thesubstrate, and (iii) prohibiting said holder, after the position of saidholder relative to the substrate has been corrected, from mounting thecomponent held by said holder onto the substrate when said controllermakes a judgement that said holder would make an interference with theanother component mounted on the substrate were the component held bysaid holder attempted to be mounted onto the substrate, and (iv) causingsaid holder, after the position of said holder relative to the substratehas been corrected, to mount the component held by said holder onto thesubstrate when said controller makes a judgement that said holder wouldnot make an interference with the another component mounted on thesubstrate were the component held by said holder attempted to be mountedonto the substrate.